This information from Lexicomp® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.
- Very bad and sometimes deadly liver problems have happened with this drug. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
- It is used to treat breast cancer.
- If you have an allergy to lapatinib or any other part of this drug.
- If you are allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
- If you have any of these health problems: Low potassium or magnesium levels.
- If you take any other drugs (prescription or OTC, natural products, vitamins). There are many drugs that interact with this drug, like certain drugs that are used for HIV, infections, or seizures.
- If you are breast-feeding. Do not breast-feed while you take this drug and for 1 week after your last dose.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.
- Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
- If you have upset stomach, throwing up, diarrhea, or are not hungry, talk with your doctor. There may be ways to lower these side effects.
- Diarrhea has happened with this drug. Sometimes, diarrhea has been severe and deaths have happened.
- If you have diarrhea, talk with your doctor. Do not try to treat diarrhea without first checking with your doctor.
- Have blood work checked as you have been told by the doctor. Talk with the doctor.
- You will need to have heart function tests while taking this drug. Talk with the doctor.
- Avoid grapefruit and grapefruit juice.
- If you are a man and have sex with a female who could get pregnant, protect her from pregnancy during treatment and for 1 week after your last dose.
- If you are a man and your sex partner gets pregnant while you take this drug or within 1 week after your last dose, call your doctor right away.
- This drug may cause harm to the unborn baby if you take it while you are pregnant.
- If you are able to get pregnant, a pregnancy test will be done to show that you are NOT pregnant before starting this drug. Talk with your doctor.
- Use birth control that you can trust to prevent pregnancy while taking this drug and for 1 week after your last dose.
- If you get pregnant while taking this drug or within 1 week after your last dose, call your doctor right away.
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of lung or breathing problems like shortness of breath or other trouble breathing, cough, or fever.
- Shortness of breath, a big weight gain, or swelling in the arms or legs.
- Very bad belly pain.
- Very upset stomach or throwing up.
- Severe diarrhea or diarrhea with stomach cramps, upset stomach, throwing up, fever, or fluid loss.
- Redness or irritation of the palms of hands or soles of feet.
- A type of abnormal heartbeat (prolonged QT interval) can happen with this drug. Call your doctor right away if you have a fast heartbeat, a heartbeat that does not feel normal, or if you pass out.
- A very bad skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis) may happen. It can cause very bad health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Upset stomach or throwing up.
- Not hungry.
- Hair loss.
- Dry skin.
- Back pain.
- Change in nails.
- Mouth irritation or mouth sores.
- Feeling tired or weak.
- Trouble sleeping.
- Pain in arms or legs.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.
Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.
- Take on an empty stomach.
- Take 1 hour before or 1 hour after a meal.
- Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
- Skip the missed dose and go back to your normal time.
- Do not take 2 doses at the same time or extra doses.
- Store at room temperature.
- Store in a dry place. Do not store in a bathroom.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
- If your symptoms or health problems do not get better or if they become worse, call your doctor.
- Do not share your drugs with others and do not take anyone else’s drugs.
- Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.
This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.
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